Printed filter

Abstract

A printed filter. The printed filter comprises a first resonator, a second resonator and a third resonator; each of the first resonator, the second resonator and the third resonator comprises an open-circuit segment and two short-circuit segments; each short-circuit segment of the first resonator, the second resonator and the third resonator is grounded; the two short-circuit segments of each of the first resonator and the second resonator are connected to form an L shape; the open-circuit segments of each of the first resonator and the second resonator are connected to the L shape of each to form an arrow; the two short-circuit segments of the third resonator are connected to form a straight line; the open-circuit segment of the third resonator is connected to the straight line of the third resonator to form a T shape; one of the short-circuit segments of each of the first resonator and the second resonator is parallel to the straight line of the third resonator. The printed filter provided by the present application can achieve the effects of small volume, high bandwidth and high attenuation slope.

Description

Technical Field

[0001] This invention relates to a filter, and more particularly to a printed filter. Background Technology

[0002] With increasing competition among communication products, reducing production costs has become an inevitable trend. Printed filters (such as microstrip filters) manufactured using printed circuit board (PCB) technology are small in size and cost-effective, thus widely used in communication products. Printed band-pass filters in communication products can prevent interference between signals from different frequency bands. However, traditional printed band-pass filters struggle to meet the nearly 1GHz bandwidth required to support high data rates in the UNII-1 to UNII-3 bands used in Wi-Fi. Furthermore, when the frequency of the signal to be filtered is close to the passband frequency of the band-pass filter, a larger attenuation slope at the cutoff frequency is needed to effectively suppress out-of-band signals and reduce interference with surrounding frequency bands. Traditional printed band-pass filters typically use high-order designs to achieve larger bandwidth or increased attenuation slope at the cutoff frequency, but this increases circuit area. With the trend towards miniaturization of communication products, there is a need for printed filters that are small in size, have high bandwidth, and have a high attenuation slope to solve the above problems. Summary of the Invention

[0003] In some embodiments, a printed filter is provided, comprising: a first resonator, a second resonator, and a third resonator; wherein each of the first, second, and third resonators includes an open-circuit segment and two short-circuit segments, and each short-circuit segment of the first, second, and third resonators is grounded; the two short-circuit segments of each of the first and second resonators are connected to form an L-shape; the open-circuit segments of each of the first and second resonators are connected to their respective L-shapes to form an arrow; the two short-circuit segments of the third resonator are connected to form a straight line; the open-circuit segment of the third resonator is connected to the straight line of the third resonator to form a T-shape; and one of the short-circuit segments of each of the first and second resonators is parallel to the straight line of the third resonator.

[0004] The printed filter provided by this invention can achieve the effects of small size, high bandwidth and high attenuation slope.

[0005] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0006] Figure 1 A schematic diagram of a printed filter is shown according to an embodiment of the present invention.

[0007] Figure 2A , Figure 2B as well as Figure 2C Schematic diagrams showing different morphologies of the resonator according to embodiments of the present invention.

[0008] Figure 3 A schematic diagram of a three-section structure is shown according to an embodiment of the present invention.

[0009] Figure 4A This displays the theoretical S-parameter curves calculated based on the required filter specifications.

[0010] Figure 4B The display shows the S-parameter values ​​obtained by simulating the printed filter of this invention using electromagnetic simulation software.

[0011] Explanation of key component symbols:

[0012] 100 Printed Filters

[0013] 102 Input segment

[0014] 102', 116' support segments

[0015] 104 First Resonator

[0016] 106 Second Resonator

[0017] 108 Third Resonator

[0018] 110 Fourth Resonator

[0019] 112 Fifth Resonator

[0020] 114 Sixth Resonator

[0021] 116 Output segment

[0022] 118 Through Hole

[0023] 200, 210, 220, 302, 304, 306 resonators

[0024] 300 Three-section structure

[0025] C1, C2, C3 coupling

[0026] G1 First Gap

[0027] G2 Second Gap

[0028] G3 Third Gap

[0029] 104a, 106a, 108a, 110a, 112a, 114a, 202a, 302a, 304a, 306a: Open road sections

[0030] 104b, 106b, 108b, 110b, 112b, 114b, 202b, 302b, 304b, 306b: Short-circuit sections Detailed Implementation

[0031] Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention. In addition, it should be understood that although terms such as "first," "second," and "third" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are mainly used to distinguish one element from another. Furthermore, throughout this invention, "connection" refers to a physical connection between two elements, whether direct or indirect, and "coupling" refers to two elements that are separate and not physically connected, but rather that energy coupling occurs between the elements through the induction of electric and / or magnetic fields.

[0032] This invention provides a printed filter that is small in size, has high bandwidth, and has a high attenuation slope.

[0033] Figure 1A schematic diagram of a printed filter 100 according to an embodiment of the present invention is shown. The printed filter 100 can be disposed on a substrate (e.g., a PCB). The printed filter 100 can be a bandpass filter. The printed filter 100 includes a first resonator 104, a second resonator 106, a third resonator 108, a fourth resonator 110, a fifth resonator 112, and a sixth resonator 114. The first resonator 104 includes an open-circuit segment 104a and two short-circuit segments 104b, the second resonator 106 includes an open-circuit segment 106a and two short-circuit segments 106b, the third resonator 108 includes an open-circuit segment 108a and two short-circuit segments 108b, the fourth resonator 110 includes an open-circuit segment 110a and two short-circuit segments 110b, the fifth resonator 112 includes an open-circuit segment 112a and two short-circuit segments 112b, and the sixth resonator 114 includes an open-circuit segment 114a and two short-circuit segments 114b. Each short-circuit segment 104b, 106b, 108b, 110b, 112b, and 114b can be grounded via its respective through-hole 118.

[0034] The printed filter 100 may further include an input section 102 and an output section 116. Signals transmitted from the input section 102 to the output section 116, after passing through the printed filter 100, can filter out signals other than the high and low cutoff frequencies, allowing passband signals between the high and low cutoff frequencies to pass through; this avoids interference with signals of other surrounding frequencies. The input section 102 is physically separated from and configured to be energy-coupled with the first resonator 104. The output section 116 is physically separated from and configured to be energy-coupled with the fourth resonator 110. The input section 102 may include a branch 102', and the shape of the branch 102' can be adapted to the first resonator 104 so that the input section 102 can surround at least a portion of the open-circuit section 104a of the first resonator 104, thereby increasing the coupling. Furthermore, due to its shape design, a portion of the branch 102' of the input segment 102 can be energy-coupled with the two short-circuit segments 104b of the first resonator 104 to increase the coupling amount. The output segment 116 may include the branch 116', and the shape of the branch 116' can be matched with the fourth resonator 110, such that the output segment 116 can surround at least a portion of the open-circuit segment 110a of the fourth resonator 110 to increase the coupling amount. Furthermore, due to its shape design, a portion of the branch 116' of the output segment 116 can be energy-coupled with the two short-circuit segments 110b of the fourth resonator 110 to increase the coupling amount.

[0035] The first resonator 104, the second resonator 106, the third resonator 108, the fourth resonator 110, the fifth resonator 112, and the sixth resonator 114 are physically separated from each other. One of the short-circuit segments 104b, 106b, 110b, and 112b of each of the first resonator 104, the second resonator 106, the fourth resonator 110, and the fifth resonator 112 is parallel to the straight line formed by the short-circuit segments 108b and 114b of the third resonator 108 and the sixth resonator 114, respectively.

[0036] The following basis Figure 2A , Figure 2B , Figure 2C as well as Figure 3 To describe the principle of the printed filter 100. Figure 2A , Figure 2B , Figure 2C as well as Figure 3 Can be paired Figure 1 Please refer to this as well. Figure 2A The resonator 200 is shown, comprising an open-circuit segment 202a and two short-circuit segments 202b, each short-circuit segment 202b being grounded via a respective via 118. The resonator 200 may have a resonant frequency, wherein the lengths of the open-circuit segment 202a and the short-circuit segment 202b can be designed according to the wavelength corresponding to the resonant frequency. For example, the resonator 200 may be a quarter-wavelength resonator, wherein the lengths of the open-circuit segment 202a and the short-circuit segment 202b are each approximately one-eighth of a wavelength. The impedance of the open-circuit segment 202a is approximately Z0, while the impedance of the short-circuit segment 202b is approximately 2Z0, meaning that the impedance of each short-circuit segment 202b is approximately twice that of the open-circuit segment 202a. Figure 2A The two short-circuit segments 202b are configured in parallel, so the equivalent impedance of the two parallel short-circuit segments 202b is Z0, thereby realizing the resonator 200 as a quarter-wavelength resonator with uniform impedance.

[0037] Figure 2B The resonator 210 is shown, which also includes an open-circuit section 202a and two short-circuit sections 202b, and the lengths and impedances of the open-circuit section 202a and the short-circuit section 202b are the same as those of the resonator 210. Figure 2A The arrow shape of the resonator 210 is as described above; however, the arrow shape of the resonator 210 Figure 2A The resonator is different from 200. Figure 2B In the process, two short-circuit segments 202b are connected to form an L-shape, and then the open-circuit segment 202a is connected to the L-shape to form an arrow. This arrow shape increases the coupling flexibility between resonators. Figure 2B The L-shape formed by the two short-circuit segments 202b shown has an included angle of approximately 90 degrees, but in some other embodiments, the L-shape may have an included angle of other degrees. Furthermore, Figure 2BThe open section 202a is roughly rectangular, but it may be configured in other shapes, such as step shapes or other shapes. The shape variations between the aforementioned short section 202b and the open section 202a can still be considered as forming an arrow. Figure 2B The arrow-shaped resonator 210 shown can be with Figure 1 The first resonator 104, the second resonator 106, the fourth resonator 110, and the fifth resonator 112 correspond to each other. However, it should be noted that the lengths and widths of the open-circuit segments 104a, 106a, 110a, and 112a and the short-circuit segments 104b, 106b, 110b, and 112b of the first resonator 104, the second resonator 106, the fourth resonator 110, and the fifth resonator 112 may vary due to adjustments. For example, the length or width of the open-circuit segment 104a of the first resonator 104 may differ from the length or width of the open-circuit segment 106a of the second resonator 106. As another example, the two short-circuit segments 104b of the first resonator 104 may have the same length, the two short-circuit segments 106b of the second resonator 106 may have the same length, and the lengths of the two short-circuit segments 104b of the first resonator 104 may differ from the lengths of the two short-circuit segments 106b of the second resonator 106. For the sake of simplicity, other variations in length and width will not be listed one by one.

[0038] Figure 2C The resonator 220 is shown, which also includes an open-circuit section 202a and two short-circuit sections 202b, and the lengths and impedances of the open-circuit section 202a and the short-circuit section 202b are the same as those of the resonator 220. Figure 2A The aforementioned; however, the T-shaped morphology of the resonator 220 is similar to... Figure 2A The resonator is different from 200. Figure 2C In the process, the two short-circuit segments 202b are connected to form a straight line, and then the open-circuit segment 202a is connected to form a straight line to form a T-shape. This T-shape can also increase the coupling flexibility between resonators. Figure 2C The open section 202a is generally rectangular in shape, but it may be configured in other shapes, such as step shapes or other shapes. Figure 2C The T-shaped resonator 220 shown can be with Figure 1The third resonator 108 and the sixth resonator 114 correspond to each other. However, it should be noted that the lengths and widths of the open-circuit segments 108a, 114a and the short-circuit segments 108b, 114b of the third resonator 108 and the sixth resonator 114 may vary due to adjustments. For example, the length or width of the open-circuit segment 108a of the third resonator 108 may differ from the length or width of the open-circuit segment 114a of the sixth resonator 114. As another example, the two short-circuit segments 108b of the third resonator 108 may have the same length, and the two short-circuit segments 114b of the sixth resonator 114 may have the same length, but the lengths of the two short-circuit segments 108b of the third resonator 108 may differ from the lengths of the two short-circuit segments 114b of the sixth resonator 114. For the sake of simplicity, other variations in length and width are not listed individually.

[0039] In some variant samples, Figure 2B and Figure 2C The open-circuit segment 202a and the short-circuit segment 202b in the same resonator 220 shown may have different lengths. In other words, although it was previously mentioned that the lengths of the open-circuit segment 202a and the short-circuit segment 202b are approximately one-eighth of the wavelength, in practice, the lengths of the open-circuit segment 202a and / or the short-circuit segment 202b may be changed to adjust the characteristics of the filter, resulting in different lengths of the open-circuit segment 202a and the short-circuit segment 202b. This invention incorporates such variations.

[0040] Furthermore, the length and width of the open-circuit segments (e.g., open-circuit segments 104a, 106a, 110a, 112a) and short-circuit segments (e.g., short-circuit segments 104b, 106b, 110b, 112b) of the arrow-shaped resonators (e.g., the first resonator 104, the second resonator 106, the fourth resonator 110, and the fifth resonator 112) may also differ from those of the open-circuit segments (e.g., open-circuit segments 108a, 114a) and short-circuit segments (e.g., short-circuit segments 108b, 114b) of the T-shaped resonators (e.g., the third resonator 108 and the sixth resonator 114).

[0041] Figure 3 The diagram shows a trisection 300 formed by two arrow-shaped resonators 302 and 304 and a T-shaped resonator 306. A single trisection 300 already provides filtering, but multiple trisections 300 can be cascaded to enhance the filtering characteristics. Figure 3 Can be paired Figure 1 Please refer to this as well. Figure 1 It can be viewed as two series-connected three-section structures 300, where Figure 3 The resonators 302 and 304 can correspond to Figure 1The first resonator 104 and the second resonator 106, or corresponding to the fourth resonator 110 and the fifth resonator 112. Furthermore... Figure 3 The resonator 306 can correspond to Figure 1 The third resonator 108 or the sixth resonator 114. (Reference) Figure 3 Resonator 302 includes an open-circuit segment 302a and two short-circuit segments 302b; resonator 304 includes an open-circuit segment 304a and two short-circuit segments 304b; and resonator 306 includes an open-circuit segment 306a and two short-circuit segments 306b. One of the short-circuit segments 302b and 304b of each of resonators 302 and 304 may be parallel to the straight line formed by the two short-circuit segments 306b of resonator 306. Resonators 302, 304, and 306 are physically separated but can be energy-coupled, wherein the energy coupling occurs in… Figure 3 This is represented as coupling C1, coupling C2, and coupling C3. Figure 3 In this embodiment, resonators 302 and 304 are coupled via short-circuit segments 302b and 304b (C1); resonators 304 and 306 are coupled via short-circuit segments 304b and 306b (C2); and resonators 306 and 302 are coupled via short-circuit segments 306b and 302b (C3). A first gap G1 exists between resonators 302 and 304, a second gap G2 exists between resonators 304 and 306, and a third gap G3 exists between resonators 302 and 306. The minimum value of the first gap G1 may be the same as or different from the minimum value of the second gap G2; the minimum value of the first gap G1 may be the same as or different from the minimum value of the third gap G3; and the minimum value of the second gap G2 may be the same as or different from the minimum value of the third gap G3. For example, in some embodiments, the minimum value of the third gap G3 may be greater than the minimum value of the first gap G1 or the minimum value of the second gap G2. The sizes of the first gap G1, the second gap G2, and the third gap G3 may directly or indirectly affect the following characteristics of the three-section structure 300: the coupling amount between conductors C1-C3, bandwidth, insertion loss, stopband attenuation, transmission zero, etc. The length and width of open sections 302a, 304a, 306a and short sections 302b, 304b, 306b will also affect the characteristics of the three-section structure 300, such as resonant frequency and coupling amount. The above theoretical examples are for reference only. In actual situations, various characteristics of the filter may be interrelated, so that the length and width of each resonator and the gap between resonators all affect the above characteristics.

[0042] Figure 3The three-section structure 300 shown can generate a transmission zero in the out-of-band region. Figure 1 The printed filter 100 shown is formed by cascading two three-section structures 300 together, which can generate two transmission zeros in the out-of-band region to provide sufficient out-of-band suppression. The transmission zeros will be discussed later. Figure 4A Further description: The series connection of two three-section structures 300 can be achieved through open-circuit coupling of the resonators. For example... Figure 1 As shown, the third resonator 108 and the sixth resonator 114 are configured to couple energy via their respective open sections 108a and 114a to connect two three-section structures in series.

[0043] Figure 4A Displays the theoretical S-parameter curves calculated based on the required filter specifications. Figure 4B The display shows the S-parameter values ​​obtained by simulating the printed filter 100 of the present invention using electromagnetic simulation software. Figure 4B The results obtained should be as close as possible to... Figure 4A The S-parameter is a curve. It is often used to evaluate the transmission and reflection of one or more ports in a circuit. Figure 4A and Figure 4B The displayed S-parameters include S11 and S21, where S11 can be used to evaluate the reflection characteristics of the signal in the input segment 102, and S21 can be used to evaluate the transmission characteristics of the signal from the input segment 102 to the output segment 116.

[0044] like Figure 4A As shown, the goal is to design a bandpass filter that generates a passband in the approximately 5180MHz to 5835MHz frequency band, allowing passband signals to pass through while filtering out signals outside the passband. This design can meet the bandwidth requirements of Wi-Fi in the UNII-1 to UNII-3 frequency bands. Figure 4A In the passband shown between 5180MHz and 5835MHz, S11 is approximately -20dB to -50dB, and S21 is approximately 0dB. This indicates that signals in the passband frequency receive few reflections at input segment 102, and most signals can be transmitted from input segment 102 to output segment 116 without attenuation. Regarding out-of-band characteristics, since the goal is to effectively filter signals above 6GHz while allowing signals between 5180MHz and 5835MHz to pass, generating a high attenuation slope in the narrow frequency band between 5835MHz and 6GHz is one of the challenges in bandpass filter design. As previously mentioned, cascading two three-section structures 300 can generate two transmission zeros, which correspond to... Figure 4AThe S21 parameters are located at approximately 5980MHz and 6090MHz. These two transmission zeros can enhance the filtering effect near 6GHz, resulting in an out-of-band attenuation of approximately 40dB at approximately 5900MHz.

[0045] Figure 4B The display shows the S-parameter values ​​obtained by simulating the printed filter 100 of the present invention using electromagnetic simulation software. Figure 4B It can be seen that the passband bandwidth is close to 1 GHz, while an out-of-band attenuation of about 45 dB can be generated at 6105 MHz. Although Figure 4B The results shown were not as... Figure 4A The two transmission zeros near 6 GHz are clearly visible, but the out-of-band suppression effect still exists. Figure 4B The S-parameters shown are for reference only, but the S-parameters measured by the printed filter 100 in actual use will be affected by the size of each resonator and the gap between the resonators. Nevertheless, the printed filter 100 of the present invention can achieve the effects of small size, high bandwidth and high attenuation slope.

[0046] The scope of the claims of this invention is not limited to the above description. Therefore, all equivalent technical changes made based on the description and drawings of this invention are included within the scope of the claims of this invention.

Claims

1. A printed filter, the printed filter comprising: The first resonant body; A second resonator; as well as A third resonant body; Each of the first resonator, the second resonator, and the third resonator includes an open-circuit section and two short-circuit sections, and each of the short-circuit sections of the first resonator, the second resonator, and the third resonator is grounded; The two short-circuit segments of the first resonator and the second resonator are connected to form an L-shape; The open-circuit segments of the first resonator and the second resonator are connected to their respective L-shapes to form an arrow; The two short-circuited segments of the third resonator are connected to form a straight line; The open-circuit segment of the third resonator connects to the straight line of the third resonator to form a T-shape; and One of the short-circuit segments of the first resonator and the second resonator is parallel to the straight line of the third resonator.

2. The printed filter of claim 1, further comprising: A fourth resonator; A fifth resonant body; as well as A sixth resonant body; Each of the fourth, fifth, and sixth resonators includes an open-circuit segment and two short-circuit segments, and each of the short-circuit segments of the fourth, fifth, and sixth resonators is grounded. The two short-circuit segments of the fourth and fifth resonators are connected to form an L-shape; The open-circuit segments of the fourth and fifth resonators are connected to their respective L-shapes to form an arrow; The two short-circuited segments of the sixth resonator are connected to form a straight line; The open-circuit segment of the sixth resonator connects to the straight line of the sixth resonator to form a T-shape; and One of the short-circuit segments of the first, second, fourth, and fifth resonators is parallel to the straight line of the third and sixth resonators, respectively.

3. The printed filter of claim 2, wherein the first resonator, the second resonator, the third resonator, the fourth resonator, the fifth resonator, and the sixth resonator are physically separated from each other.

4. The printed filter of claim 1, wherein the first resonator, the second resonator, and the third resonator are configured to be energy-coupled to each other via their respective two short-circuit sections.

5. The printed filter of claim 2, wherein the fourth resonator, the fifth resonator, and the sixth resonator are configured to be energy-coupled to each other via their respective two short-circuit sections.

6. The printed filter of claim 2, wherein the third resonator and the sixth resonator are configured to perform energy coupling via their respective open sections.

7. The printed filter of claim 1, wherein the two short-circuit segments of the first resonator have the same length, the two short-circuit segments of the second resonator have the same length, and the length of the two short circuits of the first resonator is different from the length of the two short circuit segments of the second resonator.

8. The printed filter of claim 2, wherein the open-circuit segment of the third resonator has a length, the open-circuit segment of the sixth resonator has a length, and the length of the open-circuit segment of the third resonator is different from the length of the open-circuit segment of the sixth resonator.

9. The printed filter of claim 2, wherein the open-circuit segment of the third resonator has a width, the open-circuit segment of the sixth resonator has a width, and the width of the open-circuit segment of the third resonator is different from the width of the open-circuit segment of the sixth resonator.

10. The printed filter of claim 1, wherein a first gap is formed between the first resonator and the second resonator, a second gap is formed between the second resonator and the third resonator, and a third gap is formed between the first resonator and the third resonator, wherein: The minimum value of the first gap is different from the minimum value of the second gap; The minimum value of the first gap is different from a minimum value of the third gap; or The minimum value of the second gap is different from the minimum value of the third gap.

11. The printed filter of claim 1, wherein the L-shape has an angle of 90 degrees.

12. The printed filter of claim 1, wherein the first resonator has a resonant frequency, and the open-circuit segment and the two short-circuit segments of the first resonator have the same length, the length being equal to one-eighth of a wavelength corresponding to the resonant frequency.

13. The printed filter of claim 2, further comprising: One input segment; and One output segment; The input segment is separated from the first resonator body, and the input segment is configured to be energy-coupled with the first resonator body; and The output segment is separated from the fourth resonator entity and is configured to be energy-coupled with the fourth resonator.

14. The printed filter of claim 13, wherein the input segment surrounds at least a portion of the open-circuit segment of the first resonator, and the output segment surrounds at least a portion of the open-circuit segment of the fourth resonator.

15. The printed filter of claim 14, wherein the input segment and the output segment each include a branch segment, a portion of the branch segment of the input segment is energy-coupled to the two short-circuit segments of the first resonator, and a portion of the branch segment of the output segment is energy-coupled to the two short-circuit segments of the fourth resonator.

16. The printed filter of claim 1, wherein the impedance of each of the two short-circuit segments of the first resonator, the second resonator, or the third resonator is twice the impedance of the open-circuit segment.

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